package org.apache.bcel.verifier.structurals;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache BCEL" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
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 *
 * 5. Products derived from this software may not be called "Apache",
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 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */


/**
 * This class represents a JVM execution frame; that means,
 * a local variable array and an operand stack.
 *
 * @version $Id: Frame.java,v 1.2 2006/09/04 15:43:18 andos Exp $
 * @author <A HREF="http://www.inf.fu-berlin.de/~ehaase"/>Enver Haase</A>
 */
 
public class Frame{

	/**
	 * For instance initialization methods, it is important to remember
	 * which instance it is that is not initialized yet. It will be
	 * initialized invoking another constructor later.
	 * NULL means the instance already *is* initialized.
	 */
	protected static UninitializedObjectType _this;

	/**
	 *
	 */
	private LocalVariables locals;

	/**
	 *
	 */
	private OperandStack stack;

	/**
	 *
	 */
	public Frame(int maxLocals, int maxStack){
		locals = new LocalVariables(maxLocals);
		stack = new OperandStack(maxStack);
	}

	/**
	 *
	 */
	public Frame(LocalVariables locals, OperandStack stack){
		this.locals = locals;
		this.stack = stack;
	}

	/**
	 *
	 */
	protected Object clone(){
		Frame f = new Frame(locals.getClone(), stack.getClone());
		return f;
	}

	/**
	 *
	 */
	public Frame getClone(){
		return (Frame) clone();
	}

	/**
	 *
	 */
	public LocalVariables getLocals(){
		return locals;
	}

	/**
	 *
	 */
	public OperandStack getStack(){
		return stack;
	}

	/**
	 *
	 */
	public boolean equals(Object o){
		if (!(o instanceof Frame)) return false; // implies "null" is non-equal.
		Frame f = (Frame) o;
		return this.stack.equals(f.stack) && this.locals.equals(f.locals);
	}

	/**
	 * Returns a String representation of the Frame instance.
	 */
	public String toString(){
		String s="Local Variables:\n";
		s += locals;
		s += "OperandStack:\n";
		s += stack;
		return s;
	}
}
